Background TP53-mutated acute myeloid leukaemia is associated with poor outcomes. Eprenetapopt (APR-246) is a first-in-class, small-molecule p53 reactivator. We aimed to evaluate the combination of eprenetapopt and venetoclax with or without azacitidine in patients with TP53-mutated acute myeloid leukaemia. Methods This phase 1, multicentre, open-label, dose-finding and cohort expansion study was done at eight academic research hospitals in the USA. Inclusion criteria were age of at least 18 years; at least one pathogenic TP53 mutation; treatment-naive acute myeloid leukaemia according to the 2016 WHO classification; an ECOG performance status of 0-2; and a life expectancy of at least 12 weeks. In dose-finding cohort 1 patients received previous therapy with hypomethylating agents for myelodysplastic syndromes. In dose-finding cohort 2, previous use of hypomethylating agents was not permitted. Treatment cycles were 28 days. Patients in cohort 1 received intravenous eprenetapopt 4.5 g/day on days 1-4 and oral venetoclax 400 mg/day on days 1-28; those in cohort 2 also received subcutaneous or intravenous azacitidine 75 mg/m(2) on days 1-7. The expansion part of the study proceeded with patients enrolled as in cohort 2. Primary endpoints were safety in all cohorts (assessed in patients receiving at least one dose of assigned treatment) and complete response in the expansion cohort (assessed in patients who completed at least one treatment cycle and had at least one post-treatment clinical response assessment). The trial is registered with ClinicalTrials.gov, NCT04214860, and is complete. Findings Between Jan 3, 2020, and July 22, 2021, 49 patients were enrolled across all cohorts. Six patients were initially enrolled into each of dose-finding cohorts 1 and 2; after no dose-limiting toxicities were observed, cohort 2 was expanded to enrol an additional 37 patients. The median age was 67 years (IQR 59-73). 24 (49%) of 49 patients were female and 25 (51%) male, and 40 (82%) were White. At data cutoff (Oct 1, 2021), the median length of follow-up was 9.5 months (IQR 6.1-11.5). No dose-limiting toxicities were recorded and the recommended phase 2 dose for eprenetapopt combinations was 4.5 g/day on days 1-4. Across all patients, adverse events of grade 3 or worse occurring in at least 20% of patients were febrile neutropenia (23 [47%] of 49 patients), thrombocytopenia (18 [37%] patients), leukopenia (12 [25%] patients), and anaemia (11 [22%] patients). Treatment-related serious adverse events occurred in 13 (27%) of 49 patients and there was one (2%) treatment-related death (sepsis). 25 (64%, 95% CI 47-79) of 39 patients had an overall response with eprenetapopt and venetoclax with azacytidine; 15 (38%, 23-55) had a complete response. Interpretation Eprenetapopt and venetoclax with azacitidine had an acceptable safety profile and encouraging activity, supporting further frontline evaluation of this combination in the treatment of TP53-mutated acute myeloid leukaemia. Copyright (c) 2023 The Author(s). Published by Elsevier Ltd.

Psoriasis, an immune-mediated inflammatory disease, affects nearly 125 million people globally. The interleukin (IL)-17A homodimer is a key driver of psoriasis and other autoimmune diseases, including psoriatic arthritis, axial spondyloarthritis, hidradenitis suppurativa, and uveitis. Treatment with monoclonal antibodies (mAbs) against IL-17A provides an improvement in the Psoriasis Area and Severity Index compared to conventional systemic agents. In this study, the AffibodyⓇ technology was used to identify and optimize a novel, small, biological molecule comprising three triple helical affinity domains, izokibep (previously ABY-035), for the inhibition of IL-17A signaling. Preclinical studies show that izokibep, a small 18.6 kDa IL-17 ligand trap comprising two IL-17A-specific Affibody domains and one albumin-binding domain, selectively inhibits human IL-17A in vitro and in vivo with superior potency and efficacy relative to anti-IL-17A mAbs. A Phase 1 first-in-human study was conducted to establish the safety, pharmacokinetics, and preliminary efficacy of izokibep, when administered intravenously and subcutaneously as single doses to healthy subjects, and as single intravenous and multiple subcutaneous doses to patients with psoriasis (NCT02690142; EudraCT No: 2015-004531-13). Izokibep was well tolerated with no meaningful safety concerns identified in healthy volunteers and patients with psoriasis. Rapid efficacy was seen in all psoriasis patients after one dose which further improved in patients receiving multiple doses. A therapeutic decrease in joint pain was also observed in a single patient with concurrent psoriatic arthritis. The study suggests that izokibep has the potential to safely treat IL17A-associated diseases such as psoriasis, psoriatic arthritis, axial spondyloarthritis, hidradenitis suppurativa, and uveitis.

PURPOSE Outcomes are poor in TP53-mutant (m TP53) acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS), even after allogeneic hematopoietic stem-cell transplant (HCT). Eprenetapopt (APR-246) is a first-in-class, small-molecule p53 reactivator. PATIENTS AND METHODS We conducted a phase II, multicenter, open-label trial to assess efficacy and safety of eprenetapopt combined with azacitidine as maintenance therapy after HCT (ClinicalTrials.gov identifier: NCT03931291 ). Patients with m TP53 MDS or AML received up to 12 cycles of eprenetapopt 3.7 g once daily intravenously on days 1-4 and azacitidine 36 mg/m2 once daily intravenously/subcutaneously on days 1-5 in 28-day cycles. The primary outcomes were relapse-free survival (RFS) and safety. RESULTS Of the 84 patients screened for eligibility before HCT, 55 received a transplant. Thirty-three patients ultimately received maintenance treatment (14 AML and 19 MDS); the median age was 65 (range, 40-74) years. The median number of eprenetapopt cycles was 7 (range, 1-12). With a median follow-up of 14.5 months, the median RFS was 12.5 months (95% CI, 9.6 to not estimable) and the 1-year RFS probability was 59.9% (95% CI, 41 to 74). With a median follow-up of 17.0 months, the median overall survival (OS) was 20.6 months (95% CI, 14.2 to not estimable) and the 1-year OS probability was 78.8% (95% CI, 60.6 to 89.3). Thirty-day and 60-day mortalities from the first dose were 0% and 6% (n = 2), respectively. Acute and chronic (all grade) graft-versus-host disease adverse events were reported in 12% (n = 4) and 33% (n = 11) of patients, respectively. CONCLUSION In patients with m TP53 AML and MDS, post-HCT maintenance therapy with eprenetapopt combined with azacitidine was well tolerated. RFS and OS outcomes were encouraging in this high-risk population.

Abstract Background Mutations in the tumor suppressor gene TP53 are found in up to 20% of patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). Allogeneic hematopoietic SCT remains the only potentially curative therapy however outcomes remain poor, with a 1-year relapse-free survival (RFS) of ~30% and median overall survival (OS) of ~8 months. Prior data on post-SCT maintenance therapies, including AZA, have failed to demonstrate improved post-SCT outcomes. Eprenetapopt, a small molecule p53 stabilizer, targets cellular redox balance resulting in tumor cell apoptosis and ferroptosis as well as immune modulation of the tumor microenvironment. Pre-clinical data demonstrates synergistic myeloid cell cytotoxicity in vitro and in vivo AML burden reduction when eprenetapopt is combined with AZA. Additionally, the known tolerability of this combination in AML/MDS patients makes it an attractive maintenance strategy. Methods This is a multi-center, open label, Phase II clinical trial to assess the safety and efficacy of eprenetapopt in combination with AZA as maintenance therapy after SCT for patients with TP53 mutant AML and MDS. Patients with MDS and AML with a known TP53 mutation were prescreened prior to SCT and protocol eligibility was confirmed post-SCT. Treatment consisted of up to 12 cycles of eprenetapopt 3.7 g/day Days 1-4 with AZA 36 mg/m 2/day IV/SC on Days 1-5 every 28 days. The primary objectives of this study are to assess RFS and the safety and tolerability of the combination. Additional endpoints include OS, time to progression (TTP), non-relapse mortality (NRM) and cumulative incidence of acute and chronic graft-versus-host disease (GVHD). Results The study enrolled a total of 33 patients (19 MDS, 14 AML) for active therapy. Demographics across all patients included median age 65 years (range: 40-74), 64% males, and Karnofsky performance status of ≥ 80 in 79%. The majority (76%) received a reduced intensity conditioning regimen. At initial diagnosis, 97% (32) had TP53 mutations, 9% (3) had >1 TP53 mutation, 82% (27) had complex cytogenetics (>=3), 45% (15) had chromosome (chr) 17, 76% (25) had chr 5, and 45% (15) had chr 7 abnormalities. Among 25 patients with available molecular data from a pre-SCT sample, 22 (88%) patients had a residual detectable TP53 gene mutation, 8 (36%) had > 1 TP53 mutation, and 9 (36%) patients had non-TP53 gene mutations: ASXL1 (2 ), JAK2 (4), DNMT3A (3), IDH2 (2), IDH1 (2), NRAS (1) and SF3B1 (1). As of the data cutoff date of 22 June 2021, patients completed a median of 7 cycles (1,12) of study treatment with 6 patients (18.2%) remaining on study treatment. The primary reasons for study treatment discontinuation among 27 patients, were completion of 12 cycles of treatment (9) and disease relapse (9). With median duration of RFS follow up of 413 days the median RFS was 368 days [95% CI (233-not evaluable)] and the 1-year RFS was 58%. With median duration of OS follow up of 429 days the median OS was 586 days [95% CI (369-not evaluable)] and 1-year OS 79%. All-grade treatment emergent adverse events (TEAEs) occurring in ≥20% of patients included nausea (61%), platelet count decreased (49%), vomiting (46%), anemia, dizziness, and white blood cell count decreased (39% each), fatigue (36%), diarrhea and tremor (33% each), cough, neutrophil count decreased, pruritus, and pyrexia (24% each), abdominal pain, constipation, decreased appetite, headache and hypocalcemia (21% each). Grade ≥3 TEAEs in ≥10% of patients were platelet count decreased (36%), white blood cell count decreased (33%), anemia (27%), neutrophil count decreased (24%), thrombocytopenia and hypertension (12% each). SAEs in ≥2 patients were pyrexia (12%), febrile neutropenia and dyspnea (6% each). Two patients (6%) experienced TEAEs leading to discontinuation of study treatment. Acute and chronic GVHD events of any grade were reported in 12% and 30% of patients, respectively. Conclusions Post-SCT maintenance therapy with eprenetapopt in combination with AZA was safe and tolerable with favorable results in patients with TP53 mutant MDS and AML, with 9 patients completing 12 cycles of therapy at the data cutoff date and the majority of reported TEAEs comprising known complications of high-risk MDS and AML patients in the post-SCT period. In addition, the observed RFS and OS data are highly encouraging compared to the historical outcomes for this high-risk group of patients with unmet medical need. Disclosures Mishra: Novartis: Research Funding. DeZern: Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Taiho: Consultancy, Membership on an entity's Board of Directors or advisory committees. Byrne: Karyopharm: Research Funding. Chen: Gamida: Consultancy; Incyte: Consultancy. Gallacher: Aprea Therapeutics: Current Employment, Current equity holder in publicly-traded company. Wennborg: Aprea Therapeutics: Current Employment, Current equity holder in publicly-traded company. Kaylor Hickman: Aprea Therapeutics: Current Employment, Current equity holder in publicly-traded company. Attar: Aprea Therapeutics: Current Employment, Current equity holder in publicly-traded company. Fernandez: Incyte: Honoraria. OffLabel Disclosure: The presentations includes the use of experimental agent eprenetapopt (APR-246) and the agent azacitidine in the post-transplant maintenance setting.

Abstract Background Mutations in the tumor suppressor gene TP53 are found in up to 20% of patients with AML, 30-40% of pts with secondary AML, and are associated with extremely poor overall survival (OS) of < 6 months. VEN + hypomethylating agent (HMA) combinations are associated with a 20-25% complete remission (CR) rate in TP53 mutant AML (Wei, 2018; DiNardo, 2020) though VEN + HMA has not improved OS over AZA alone. Eprenetapopt, a small molecule p53 stabilizer, targets cellular redox balance resulting in tumor cell apoptosis and ferroptosis as well as immune modulation of the tumor microenvironment. Pre-clinically, eprenetapopt interacts synergistically with AZA and VEN to induce myeloid cell death in vitro and significantly reduces tumor burden when combined with AZA in a murine AML xenotransplant model. Methods This is a multi-center, open-label, dose-finding and expansion study to determine the safety and preliminary efficacy of eprenetapopt in combination with VEN and AZA in TP53 mutant AML. This study included two 3+3 dose-finding safety lead in cohorts of pts with previously untreated TP53 mutant AML followed by an expansion. Dose limiting toxicities (DLTs) were assessed during C1 and included prolonged myelosuppression in the absence of disease and grade ≥3 non-hematologic toxicity not recovering to grade ≤1. Pts in Safety Cohort 1 (SC1) received 1 prior line of HMA therapy for MDS and Safety Cohort 2 (SC2) had no prior HMA. Treatment consisted of concurrent eprenetapopt at 4.5 g/day D 1-4 with VEN 400 mg PO QD for SC1 while SC2 also received AZA 75 mg/m 2 IV/SC D 1-7. Cycles were 28 days. Following the safety cohorts, Expansion Cohort 2 (eprenetapopt + AZA + VEN) enrolled pts with previously untreated AML without prior HMA. Primary endpoints include determination of DLTs, frequency and severity of treatment-emergent adverse events (TEAEs), and recommended eprenetapopt dose for expansion. Secondary endpoints include rates of CR and CR+ CRi (CR with incomplete blood count recovery). Results As of the data cutoff date of 22 June 2021, 47 pts were enrolled, 44 received at least 1 dose of eprenetapopt, and 9 remained on the triplet combination The median age was 67 years (27-81), 52.3% were male, 77% had performance status ≤1, 55% had secondary AML, and 30% had therapy-related AML. Median aspirate blasts was 28%, ANC 0.42 K/uL, hemoglobin 79 g/L, and plts 24.5 K/uL. Complex karyotype (≥3) was detected in 36/39 pts (92%) and abnormal chromosomes 5, 7, and 17 in 28 (72%), 12 (31%), and 20 pts (51%), respectively. Median TP53 VAF was 48% (0,87) with 71%, 16%, 7%, and 5% having missense, frameshift, nonsense, and splice mutations, respectively. Across all cohorts, disease progression or relapse (19) and hematopoietic stem cell transplant (7) were the primary reasons for treatment discontinuation. There were no DLTs observed in the 6 pts in SC1 and in the 6 pts in SC2. All-grade TEAEs in ≥30% included nausea (66%), febrile neutropenia (52%), diarrhea (50%), decreased appetite (41%), constipation and vomiting (39% each), hypokalemia (36%), hypotension, platelet count decreased, and peripheral edema (32% each), and dizziness and cough (30% each). Grade ≥3 TEAEs in ≥20% were febrile neutropenia (52%), platelet count decreased (30%), and anemia (21%). Four pts (9%) experienced TEAEs leading to study treatment discontinuation. Eleven pts experienced a TEAE leading to death, with sepsis (n=2) being the only fatal TEAE reported in >1 pt. No fatal TEAE was assessed as treatment related. The 30-day mortality rate was 9%. There was 1 CR and 1 CRi among the 6 pts who received eprenetapopt + VEN. Preplanned efficacy analysis of the first 30 efficacy evaluable pts who received eprenetapopt + VEN + AZA demonstrated CR rate of 37% and CR +CRi rate of 53% with median duration 118 days (95% CI 60, NE) and 128 days (95% CI 57, NE), respectively. Based on the number of reported CRs, 11, the study met the Simon 2-stage efficacy criteria discriminating a target CR rate of >40% from a failure CR rate of <20%. Conclusions Eprenetapopt plus VEN with and without AZA was tolerated by pts as demonstrated by absence of DLTs across safety cohorts and by an emerging safety profile consistent with events attributable to the underlying disease as well as those known to occur with VEN and AZA therapy. In addition, the triplet regimen demonstrated highly encouraging efficacy data and met the Simon-2 stage CR threshold, warranting further study in this population with unmet medical need. Disclosures Goldberg: Arog: Research Funding; Celularity: Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Aprea: Research Funding; DAVA Oncology: Honoraria; Prelude Therapeutics: Research Funding; Aptose: Consultancy, Research Funding; Pfizer: Research Funding; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Winer: Takeda: Consultancy; Novartis: Consultancy; Abbvie: Consultancy. Altman: Astellas: Honoraria, Research Funding; Aptos: Research Funding; Loxo: Research Funding; Aprea: Research Funding; Biosight: Membership on an entity's Board of Directors or advisory committees, Other: reimbursement for travel, Research Funding; Kura Oncology: Membership on an entity's Board of Directors or advisory committees, Research Funding; Kartos Therapeutics: Research Funding; ImmunoGen: Research Funding; Syros: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; Boehringer Ingelheim: Research Funding; Celgene: Research Funding; ALX Oncology Inc.: Research Funding; Fujifilm: Research Funding; Glycomimetics: Other: data monitoring committee; Abbvie: Honoraria, Research Funding. Fathi: AbbVie: Consultancy, Honoraria, Research Funding; Agios: Consultancy, Honoraria, Research Funding; Servier: Research Funding; Celgene/BMS: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Blueprint: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Daiichi Sankyo: Consultancy, Honoraria; Genentech: Consultancy, Honoraria; Trillium: Consultancy, Honoraria; Kura: Consultancy, Honoraria; Foghorn: Consultancy, Honoraria; Kite: Consultancy, Honoraria; Morphosys: Consultancy, Honoraria; Ipsen: Consultancy, Honoraria. Odenike: Celgene, Incyte, AstraZeneca, Astex, NS Pharma, AbbVie, Gilead, Janssen, Oncotherapy, Agios, CTI/Baxalta, Aprea: Research Funding; AbbVie, Celgene, Impact Biomedicines, Novartis, Taiho Oncology, Takeda: Consultancy. Roboz: Astellas: Consultancy; Celgene: Consultancy; Mesoblast: Consultancy; Actinium: Consultancy; Blueprint Medicines: Consultancy; AstraZeneca: Consultancy; Astex: Consultancy; Amgen: Consultancy; Janssen: Consultancy; Helsinn: Consultancy; Janssen: Research Funding; Jasper Therapeutics: Consultancy; MEI Pharma - IDMC Chair: Consultancy; Agios: Consultancy; Bayer: Consultancy; Jazz: Consultancy; AbbVie: Consultancy; Daiichi Sankyo: Consultancy; Bristol Myers Squibb: Consultancy; Novartis: Consultancy; Glaxo SmithKline: Consultancy; Otsuka: Consultancy; Pfizer: Consultancy; Roche/Genentech: Consultancy. Gallacher: Aprea Therapeutics: Current Employment, Current equity holder in publicly-traded company. Wennborg: Aprea Therapeutics: Current Employment, Current equity holder in publicly-traded company. Kaylor Hickman: Aprea Therapeutics: Current Employment, Current equity holder in publicly-traded company. Attar: Aprea Therapeutics: Current Employment, Current equity holder in publicly-traded company. Sallman: Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Aprea: Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; Magenta: Consultancy; Intellia: Membership on an entity's Board of Directors or advisory committees; Shattuck Labs: Membership on an entity's Board of Directors or advisory committees; Syndax: Membership on an entity's Board of Directors or advisory committees; Kite: Membership on an entity's Board of Directors or advisory committees; Incyte: Speakers Bureau; Takeda: Consultancy. OffLabel Disclosure: This study discusses the off-label use of eprenetapopt in the treatment of TP53 mutant AML.

Abstract Background Albumin is commonly used as a carrier platform for drugs to extend their circulatory half-lives and influence their uptake into tissues that have altered permeability to the plasma protein. The albumin-binding domain (ABD) protein, which binds in vivo to serum albumin with high affinity, has proven to be a versatile scaffold for engineering biopharmaceuticals with a range of binding capabilities. In this study, the ABD protein equipped with a mal-DOTA chelator (denoted ABY-028) was radiolabeled with gallium-68 (68Ga). This novel radiotracer was then used together with positron emission tomography (PET) imaging to examine variations in the uptake of the ABD-albumin conjugate with variations in endothelial permeability. Results ABY-028, produced by peptide synthesis in excellent purity and stored at − 20 °C, was stable for 24 months (end of study). [68Ga]ABY-028 could be obtained with labeling yields of > 80% and approximately 95% radiochemical purity. [68Ga]ABY-028 distributed in vivo with the plasma pool, with highest radioactivity in the heart ventricles and major vessels of the body, a gradual transport over time from the circulatory system into tissues and elimination via the kidneys. Early [68Ga]ABY-028 uptake differed in xenografts with different vascular properties: mean standard uptake values (SUVmean) were initially 5 times larger in FaDu than in A431 xenografts, but the difference decreased to 3 after 1 h. Cutaneously administered, vasoactive nitroglycerin increased radioactivity in the A431 xenografts. Heterogeneity in the levels and rates of increases of radioactivity uptake was observed in sub-regions of individual MMTV-PyMT mammary tumors and in FaDu xenografts. Higher uptake early after tracer administration could be observed in lower metabolic regions. Fluctuations in the increased permeability for the tracer across the blood-brain-barrier (BBB) direct after experimentally induced stroke were monitored by PET and the increased uptake was confirmed by ex vivo phosphorimaging. Conclusions [68Ga]ABY-028 is a promising new tracer for visualization of changes in albumin uptake due to disease- and pharmacologically altered vascular permeability and their potential effects on the passive uptake of targeting therapeutics based on the ABD protein technology.

Background: Outcomes for CLL pts with TP53 aberrancy including deletion of 17p (del17p) or TP53 mutations treated with chemo+/-immunotherapy (CIT) have been historically poor. Despite improvements, pts with TP53 aberrancy treated with novel agent-based regimens such as ibrutinib (ibr), acalabrutinib and venetoclax (ven), still have inferior outcomes as compared to pts with intact TP53. In 5 year follow-up data from relapsed/refractory (R/R) CLL pts treated with ibr, pts with del17p had a shorter median progression free survival (PFS) and overall survival (OS) (26 and 57 months) vs. the overall cohort (median PFS 51 months, OS not reached, O'Brien et al Blood 2018). Additionally, for R/R CLL pts treated with 24 months of ven and rituximab (VR), del17p and/or a TP53 mutation was associated with an increased risk of CLL progression after stopping ven (p=0.01, Kater et al JCO 2019). In addition, pts with mantle cell lymphoma (MCL) with TP53 mutations have a poor response to CIT and autologous stem cell transplantation. In a series of MCL pts who discontinued ibr, 75% who discontinued for progression harbored TP53 alterations (Jain et al Br J Haematol 2018). These studies highlight an unmet need for improved treatments for CLL and MCL pts with TP53 mutations. APR-246 is a novel small molecule that is converted to methylene quinuclidinone (MQ), a reactive electrophile that forms a covalent bond with the p53 core domain to reactivate mutant p53 and restore wild type p53 function and apoptotic activity (Zhang et al Cell Death Disease 2018). Additionally, APR-246 has been shown to deplete glutathione and induce reactive oxygen species (Liu et al Nat Commun 2017). Clinical activity has been demonstrated in phase II studies of APR-246 + azacitadine in TP53 mutant MDS (ORR 88%, CR 61%, Sallman et al ASH 2019; ORR 75%, CR 57%, Cluzeau T et al EHA 2020). A phase I trial of APR-246 in combination with venetoclax is ongoing in AML (NCT04214860). APR-246 induces apoptosis in TP53 mutated CLL cells (Jaskova et al, Leuk Res 2020) and single agent activity in CLL has been described in the APR-246 first-in-human clinical trial (Lehmann S et al JCO 2012; Deneberg S et al Blood Canc J 2016). Study Design and Methods: This is a phase 1, open-label, 3+3 dose de-escalation and dose expansion study investigating APR-246 in combination with (cohort 1) ibrutinib or (cohort 2) VR in pts with R/R TP53 mutant CLL or MCL (Figure 1). The safety lead-in portion of the study includes two safety cohorts of CLL pts with TP53 mutations: APR-246 in combination with (1) ibrutinib (ibr), n~28 pts or (2) APR-246 in combination with VR, n=~28 pts. Treatment will be administered according to Figure 2. Eligible pts must have a TP53 mutation. Based on the results of an integrated assessment of the safety, tolerability and preliminary clinical activity in the safety lead-in cohorts, ibr and/or VR will be selected for further study in combination with APR-246 in a dose expansion portion of the study which will include pts with TP53-mutant (1) R/R CLL (n≤20) and (2) R/R MCL (≤40). The primary study endpoints will be (1) the occurrence of DLTs according to the NCI CTCAE, version 5.0, (2) the frequency of treated-emergent adverse events (AE) and SAE, and (3) the recommended phase 2 dose (RP2D) of APR-246 in combination with ibr or VR. Secondary study endpoints include pharmacokinetic parameters, the complete response rate, objective response rate, duration of response and PFS for APR-246 in combination with ibr or VR. Correlative studies are planned to examine the effect of APR-246 combinations on the p53 pathway and examine genome and transcriptome correlates of response and resistance. Patient samples will be collected at multiple timepoints to measure p53 protein expression by immunoblot of protein lysates from mononuclear cells. Specifically, p53, BCL2, BAX, NOXA and PUMA levels will be examined to assess the effect of APR-246 + ibr or VR on the p53 pathway. These studies will be complemented by BH3 profiling, a functional technique to assess the propensity of the tumor cells to undergo apoptosis and their dependence on specific anti-apoptotic proteins. Additionally, intracellular flow cytometry will evaluate the effect of the combinations on key markers within the p53 pathway. DNA and RNA sequencing will be performed to identify potential biomarkers of response. This study is planned to be open for enrollment by September 2020 at the first study site and is planned to open at up to 10 study sites. Disclosures Davids: Bristol Myers Squibb: Research Funding; Pharmacyclics: Consultancy, Research Funding; Surface Oncology: Research Funding; Merck: Consultancy; TG Therapeutics: Consultancy, Research Funding; Verastem: Consultancy, Research Funding; Syros Pharmaceuticals: Consultancy; Research to Practice: Honoraria; Zentalis: Consultancy; Genentech: Consultancy, Research Funding; Eli Lilly: Consultancy; Celgene: Consultancy; AstraZeneca: Consultancy, Research Funding; BeiGene: Consultancy; AbbVie: Consultancy; Adaptive Biotechnologies: Consultancy; Ascentage Pharma: Consultancy, Research Funding; Janssen: Consultancy; MEI Pharma: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Gilead Sciences: Consultancy; Sunesis: Consultancy. Jain:Servier: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Aprea Therapeutics: Research Funding; Precision Bioscienes: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Fate Therapeutics: Research Funding; BMS: Research Funding; BeiGene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; ADC Therapeutics: Research Funding; TG Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Verastem: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cellectis: Research Funding; AstraZeneca: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Research Funding; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Soumerai:AstraZeneca: Consultancy; AbbVie: Consultancy; TG Therapeutics: Research Funding; Beigene: Consultancy, Research Funding; BostonGene: Research Funding; Genentech/Roche: Research Funding; GlaxoSmithKine: Research Funding; Verastem: Consultancy. Gubits:Aprea Therapeutics: Current Employment. Hickman:Aprea Therapeutics: Current Employment. Wennborg:Aprea Therapeutics: Current Employment, Current equity holder in publicly-traded company. Attar:Aprea Therapeutics: Current Employment. Abdel-Wahab:Merck: Consultancy; Envisagenics Inc.: Current equity holder in private company; H3 Biomedicine Inc.: Consultancy, Research Funding; Janssen: Consultancy. Mato:TG Therapeutics: Consultancy, Other: DSMB, Research Funding; Adaptive: Consultancy, Research Funding; BeiGene: Consultancy; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; LOXO: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding.

In phase I/II-studies radiolabelled ABY-025 Affibody molecules identified human epidermal growth factor receptor 2 (HER2) expression in breast cancer metastases using PET and SPECT imaging. Here, we wanted to investigate the utility of a simple intra-image normalization using tumour-to-reference tissue-ratio (T/R) as a HER2 status discrimination strategy to overcome potential issues related to cross-calibration of scanning devices.

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Therapies targeting human epidermal growth factor receptor type 2 (HER2) have revolutionized breast cancer treatment, but require invasive biopsies and rigorous histopathology for optimal patient stratification. A non-invasive and quantitative diagnostic method such as positron emission tomography (PET) for the pre-therapeutic determination of the presence and density of the HER2 would significantly improve patient management efficacy and treatment cost. The essential part of the PET methodology is the production of the radiopharmaceutical in compliance with good manufacturing practice (GMP). The use of generator produced positron emitting (68)Ga radionuclide would provide worldwide accessibility of the agent. GMP compliant, reliable and highly reproducible production of [(68)Ga]Ga-ABY-025 with control over the product peptide concentration and amount of radioactivity was accomplished within one hour. Two radiopharmaceuticals were developed differing in the total peptide content and were validated independently. The specific radioactivity could be kept similar throughout the study, and it was 6-fold higher for the low peptide content radiopharmaceutical. Intrapatient comparison of the two peptide doses allowed imaging optimization. The high peptide content decreased the uptake in healthy tissue, in particular liver, improving image contrast. The later imaging time points enhanced the contrast. The combination of high peptide content radiopharmaceutical and whole-body imaging at 2 hours post injection appeared to be optimal for routine clinical use.

68Ga-ABY-025 is a radiolabeled Affibody molecule for in vivo diagnosis of human epidermal growth factor receptor 2 (HER2)–positive breast cancer tumors with PET. The aim of the present work was to measure the biodistribution and estimate the radiation dosimetry of 68Ga-ABY-025 for 2 different peptide mass doses in a single group of patients using dynamic and serial whole-body PET/CT. Methods: Eight patients with metastatic breast cancer were included. Each patient underwent an abdominal 45-min dynamic and 3 whole-body PET/CT scans at 1, 2, and 4 h after injection of a low peptide dose (LD) and a high peptide dose (HD), with approximately the same amount of radioactivity, in separate investigations 1 wk apart. As input to the absorbed dose calculations, volumes of interest were drawn on all clearly identifiable source organs: liver, kidneys, spleen, descending aorta, and upper large intestine. Absorbed doses were calculated using OLINDA/EXM, version 1.1. Results: Of the major organs, the highest radionuclide uptake at 1, 2, and 4 h after injection was observed in the kidneys and liver. The highest absorbed organ doses were seen in the kidneys, followed by the liver for both LD and HD 68Ga-ABY-025. Absorbed doses to liver and kidneys were slightly but significantly higher for LD. Total effective dose was 0.030 ± 0.003 mSv/MBq for LD and 0.028 ± 0.002 mSv/MBq for HD. Conclusion: The effective dose for a typical 200-MBq administration of 68Ga-ABY-025 is 6.0 mSv for LD and 5.6 mSv for HD. Therefore, from a radiation dosimetry point of view, HD is preferred for PET/CT evaluation of HER2-expressing breast cancer tumors. These effective doses are somewhat higher than earlier published values for other 68Ga-labeled tracers, such as 0.021 ± 0.003 mSv/MBq for 68Ga-DOTATATE and 68Ga-DOTATOC, mainly because of higher uptake in liver and kidney.

Purpose: Positron Emission Tomography (PET) imaging of HER2 expression could potentially be used to select patients for HER2-targed therapy, predict response based on uptake and be used for monitoring.In this phase I/II study the HER2-binding Affibody molecule ABY-025 was labeled with 68 Ga-gallium ([ 68 Ga]ABY-025) for PET to study effect of peptide mass, test-retest variability and correlation of quantified uptake in tumors to histopathology.Experimental design: Sixteen women with known metastatic breast cancer and on-going treatment were included and underwent FDG PET/CT to identify viable metastases.After iv injection of 212±46 MBq [ 68 Ga]ABY-025 whole-body PET was performed at 1, 2 and 4 h.In the first 10 patients (6 with HER2-positive and 4 with HER2-negative primary tumors), [ 68 Ga]ABY-025 PET/CT with two different doses of injected peptide was performed one week apart.In the last six patients (5 HER2-positive and 1 HER2-negative primary tumors), repeated [ 68 Ga]ABY-025 PET were performed one week apart as a test-retest of uptake in individual lesions.Biopsies from 16 metastases in 12 patients were collected for verification of HER2 expression by immunohistochemistry and in-situ hybridization.Results: Imaging 4h after injection with high peptide content discriminated HER2-positive metastases best (p<0.01).PET SUV correlated with biopsy HER2-scores (r=0.91,p<0.001).Uptake was five times higher in HER2-positive than in HER2-negative lesions with no overlap (p=0.005).The test-retest intra-class correlation was r=0.996.[ 68 Ga]ABY-025 PET correctly identified conversion and mixed expression of HER2 and targeted treatment was changed in 3 of the 16 patients.Conclusion: [ 68 Ga]ABY-025 PET accurately quantifies whole-body HER2-receptor status in metastatic breast cancer.

Accuracy of [Ga-68]ABY-025 PET/CT for determination of HER2-expression in metastatic breast cancer

Good manufacturing practice compliant production of a Ga-68-labelled Affibody agent for breast cancer imaging : first-in-human

11067 Background: In contrast to biopsies, PET imaging gives a complete and quantitative image of all the patient’s tumors and all parts of individual lesions. PET imaging of HER2 could select patients for HER2-targed therapy, predict response based on uptake and be used for monitoring. In this pivotal phase I/II study the HER2-binding Affibody molecule ABY025 was labeled with 68Ga for PET to study effect of peptide mass, test-retest variability and correlation of quantified uptake in tumors to histopathology. Methods: Sixteen women with known metastatic breast cancer and on-going treatment were included and underwent FDG PET/CT to identify viable metastases. After iv injection of 212±46 MBq 68Ga-ABY025 whole-body PET was performed at 1, 2 and 4 h. In the first 10 patients, 68Ga-ABY025 PET/CT with two different doses of unlabeled peptide was performed 1 week apart. Six had HER2-positive primary tumors and 4 were included as HER2-negative controls. In the last six patients (5 HER2-pos and 1 HER2-neg primary tumor), repeated 68Ga-ABY025 PET were done as a test-retest of uptake at 2 h in individual lesions. Primary tumors and biopsies from metastases were collected for verification of HER2 expression. Results: Scanning with the higher peptide dose at 2-4h provided better discrimination of HER2-pos metastases in all tissues (p < 0.01). Sixteen metastases in 12 patients were biopsied and evaluated by immunohistochemistry and in-situ hybridization. Uptake (SUV, mean ± SD) at 2h in these metastases was 10.9 ± 5.1 in HER2-pos (n = 7) vs 3.4±2.1 in HER2-neg (n = 9) (p = 0.001). SUV at 4h was 15.0 ± 3.4 in HER2-pos (n = 6) vs 2.9±1.9 in HER2-neg (n = 6) (p < 0.001, no overlap). The test-retest intra-class correlation was R = 0.996. 68Ga-ABY025 PET led to change in HER2-targeting treatment in 3 of the 16 patients due to receptor up- or down-regulation. Moreover, the PET data indicates occurrence of intra-patient heterogeneity of HER2-expression in several cases. Conclusions: 68Ga-ABY025 PET accurately quantifies whole-body HER2-receptor status in metastatic breast cancer. Clinical trial information: NCT01858116.

The expression status of human epidermal growth factor receptor type 2 (HER2) predicts the response of HER2-targeted therapy in breast cancer. ABY-025 is a small reengineered Affibody molecule targeting a unique epitope of the HER2 receptor, not occupied by current therapeutic agents. This study evaluated the distribution, safety, dosimetry, and efficacy of 111In-ABY-025 for determining the HER2 status in metastatic breast cancer. Methods: Seven patients with metastatic breast cancer and HER2-positive (n = 5) or -negative (n = 2) primary tumors received an intravenous injection of approximately 100 μg (∼140 MBq) of 111In-ABY-025. Planar γ-camera imaging was performed after 30 min, followed by SPECT/CT after 4, 24, and 48 h. Blood levels of radioactivity, antibodies, shed serum HER2, and toxicity markers were evaluated. Lesional HER2 status was verified by biopsies. The metastases were located by 18F-FDG PET/CT 5 d before 111In-ABY-025 imaging. Results: Injection of 111In-ABY-025 yielded a mean effective dose of 0.15 mSv/MBq and was safe, well tolerated, and without drug-related adverse events. Fast blood clearance allowed high-contrast HER2 images within 4–24 h. No anti–ABY-025 antibodies were observed. When metastatic uptake at 24 h was normalized to uptake at 4 h, the ratio increased in HER2-positive metastases and decreased in negative ones (P < 0.05), with no overlap and confirmation by biopsies. In 1 patient, with HER2-positive primary tumor, 111In-ABY-025 imaging correctly suggested a HER2-negative status of the metastases. The highest normal-tissue uptake was in the kidneys, followed by the liver and spleen. Conclusion: 111In-ABY-025 appears safe for use in humans and is a promising noninvasive tool for discriminating HER2 status in metastatic breast cancer, regardless of ongoing HER2-targeted antibody treatment.

Background: Molecular imaging, in particular, positron emission tomography (PET) provides unique possibility to non-invasively quantify the biomarkers. A small peptide, ABY-025, is targeting a unique epitope of the HER2-receptor and can be labeled with 111In or 68Ga. It is non-competitive with current antibody-targeted epitopes and is approximately 25 times smaller than an antibody and posses superior pharmacokinetics as imaging agent. We have earlier reported promising results of lesion visualization and determination of HER2 status by 111In-ABY-025/SPECT-CT in seven patients with metastatic breast cancer (MBC). As PET-CT provides superior possibilities for quantification and allows for imaging with shorter time frames, we now investigate 68Ga-ABY-025 in HER2-positive and HER2-negative MBC patients in a prospective study. The influence of the administered amount of ABY-025 on the discrimination between HER2-positive and HER2-negative metastases as well as detection rate and image contrast is investigated. The HER2 status changes will be followed at disease progression. We report here promising data on the first three patients. Patients and methods: The study considers twenty patients in two cohorts. Of the first 10 patients, 4 should have HER2-negative MBC and 6 patients HER2-positive disease. Metastases were localized by 18F-FDG/PET-CT prior HER2 imaging. Each patient (two HER2-positive and one HER-negative) underwent two subsequent examinations. First, 68Ga-ABY-025 PET/CT (ABY-025: 75±14 μg) was performed with dynamic acquisition during 0-45 minutes and static images after 1, 2 and 4 hours. The procedure was repeated after one week with a higher dose of 68Ga-ABY-025 (ABY-025: 445±10 μg) to identify the optimal dosage for the discrimination between HER2-positive and HER2-negative metastases. Blood levels of radioactivity, anti-ABY-025-antibodies, shed serum HER2 and toxicity markers were evaluated. Biopsies were taken to verify the HER2 status of the lesions. The second cohort of 10 patients (all with HER2-positive disease), will have their primary PET-CT with the optimal dose of 68Ga-ABY-025 and will, as the HER-positive from the first cohort, have a follow-up 68Ga-ABY-025 PET/CT after disease progression or, at latest, after 9 months. Results: The imaging agent was well tolerated by the patients without adverse events. The rapid blood clearance and normal tissue wash out allowed high contrast HER2 images within a few hours. The HER2 status was confirmed by histological analysis of biopsies. In one patient with HER2-negative primary tumor, imaging suggested a HER2-positive liver metastasis. The change of HER2 expression was verified with analysis of the corresponding biopsy. This finding resulted in the change of the treatment management. Preliminary validation suggests the preference of high dose ABY-025 in terms of image contrast and detection. The study is ongoing and more patients will be reported Conclusion: Preliminary results indicate strong potential of 68Ga-ABY-025 PET/CT for discriminating HER2-positive versus HER2-negative metastatic breast cancer, regardless of ongoing HER2-targeted antibody treatment. The method introduces rapid whole-body receptor mapping of primary tumor and metastases in a single examination. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-01-17.